Abstract
Camellia (Camellia oleifera Abel.) seed oil is a commonly used edible oil of China. In ancient Chinese literature, it is mentioned to be helpful for postpartum repair and lactation in women. Research on camellia seed oil (CO) as a feed additive for dairy cattle is less. We investigated the effect of CO on the expression of milk fat and protein syntheses‐related genes in differentiated bovine mammary epithelial cells (MAC‐T) using soybean oil (SO) as the control. The results showed that CO increased the expression of genes related to de novo synthesis of fatty acids including sterol regulatory element‐binding protein 1 (SREBP1), acetyl‐CoA carboxylase 1 (ACC), fatty acid synthase (FASN), lipoprotein lipase (LPL), and stearoyl‐CoA desaturase (SCD) (p < .05). Among the milk protein genes analyzed, CO increased β‐casein mRNA expression (p < .05) and decreased αS1‐casein mRNA expression (p < .05) in MAC‐T cells. CO upregulated the pathways related to milk protein synthesis with increased mRNA levels of phosphoinositide 3‐kinase (PI3K), RAC‐alpha serine/threonine‐protein kinase (AKT1), and mammalian target of rapamycin (mTOR) (p < .05) in MAC‐T cells. Ribosomal protein S6 kinase beta‐1 (S6K1) gene was upregulated, and eukaryotic initiation factor 4E (eIF4E) gene (p < .05) was downregulated with CO treatment. The mRNA expression levels of janus kinase 2 (JAK2), activator of transcription 5‐β (STAT5‐β), and E74‐like factor 5 (ELF5) were elevated in MAC‐T cells treated with CO (p < .05). Meanwhile, the protein expression levels of S6K1, STAT5‐β, phosphorylated mTOR (p‐mTOR), p‐S6K1, and p‐STAT5‐β increased in MAC‐T cells treated with CO (p < .05). In summary, CO promoted β‐casein synthesis by regulating PI3K‐mTOR‐S6K1 and JAK2‐STAT5 signaling pathways and influenced fatty acid synthesis by regulating SREBP1‐related genes in MAC‐T cells. We need to further confirm the function of CO using in vivo models.
Highlights
Camellia (Camellia oleifera Abel.) seeds have been used in China for more than 1,000 years, and the oil extracted from seeds, named camellia seed oil (CO), is a high-quality cooking oil (Li, Zhu, et al, 2012)
98 188 (FASN) (p < .05), lipoprotein lipase (LPL) (p < .05), and stearoyl-CoA desaturase (SCD) (p < .05) were upregulated in MAC-T cells treated with CO compared with control (Figure 1)
We examined the effect of CO on mRNA expression of β-casein and αS1-casein genes in MAC-T cells through Quantitative PCR (qPCR) analysis. β-casein mRNA expression in MAC-T cells increased significantly with CO treatment compared with control (p < .05; Figure 2)
Summary
Camellia (Camellia oleifera Abel.) seeds have been used in China for more than 1,000 years, and the oil extracted from seeds, named camellia seed oil (CO), is a high-quality cooking oil (Li, Zhu, et al, 2012). CO has low polyunsaturated fatty acid content, in quantity and diversity, and preserves nutritional value (Zhong et al, 2007) It contains 80.64% oleic acid as compared to 76.16% in olive oil (Wang, Zeng, Verardo, & del Mar Contreras, 2017; Zeb, 2012). The in vivo study by Liang reported that oleic acid supplementation increased sterol regulatory element-binding protein 1 (SREBP1) gene expression in bovine mammary epithelial cells (Liang et al, 2014). We speculate that CO may activate fatty acid synthesis through SREBP1-related genes and may promote milk protein synthesis via PI3K-AKT1-mTOR or JAK2-STAT5 signaling pathways. We investigate the effect of CO supplement on the expression of genes related to milk fat and protein syntheses in bovine mammary epithelial cells (MAC-T). The study has an indirect significance for the value of feed raw materials in dairy husbandry
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